Chances are if you spend much time driving, you’ve come up on a line of traffic that is stopped or slowed down due to road construction. These lines or “queues” as traffic safety professionals call them, put drivers at a high risk of rear-end crashes if they’re not paying close attention to what is up ahead. This construction season the Iowa DOT explored additional technology that can provide drivers with more detailed information about stopped or slow traffic ahead.
Since 2014, Iowa DOT has been using temporary cameras, message signs, and speed sensors, to detect traffic back-ups and automatically post roadside messages to alert drivers before they come up on slow traffic in a work zone. Dan Sprengeler, an Iowa DOT engineer who specializes in work zone safety systems, explained that sensors are installed to measure traffic speed. If these sensors detect a slowdown, there is a signal sent to lighted signs in the area that will display a message to drivers. “Depending on the traffic speed, the sign will either display a message that says, ‘Slow traffic ahead’ or ‘stopped traffic ahead’ that gives drivers additional information to take action.” An enhancement that was tested this summer was to add a sign that displayed the actual speed that the slow traffic was moving through the work zone to the roadside message.
Sprengeler continued, “We have had technology in place for several years to help drivers recognize an upcoming queue, but we are hopeful that this additional speed information will help drivers travel at more uniform speeds. Any slowdown can be annoying, but when there are wide differences in vehicle speeds, that is when there is the biggest risk for severe crashes. We really want to avoid that.”
Just like every new technology, there are bugs to be worked out, but Tim Simodynes, an Iowa DOT traffic operations Engineer said there are checks in place during the testing phase. He said, “When the signal is sent to the signs for slow or stopped traffic, the operators in our traffic management center are alerted. They can check traffic in the area and change the signs manually if needed. They are on duty 24/7/365 and ensure the accuracy of the signs.”
The speed messaging was tested on a bridge repair project on Interstate 80 just west of U.S. 71 in western Iowa. It was just the latest in a tradition of intelligent work zone innovations for Iowa. “This has been our ninth summer of providing automated queue detection and warning, and during that time we have also introduced other specialized systems,” said Simodynes. Iowa DOT has deployed automated ‘truck entering’ warning systems, travel time detection, and some of the first speed feedback signs.” “Not only do these technologies aim to give drivers information about the situation on the road, but they also transmit information back to our traffic management center and to the 511 system, “ added Simodynes. “Using that information, our technicians and engineers can make adjustments to work zones as needed and travelers logging on to 511 can see in real-time what’s happening on the road.”